(a) Field of the Invention
This invention relates to a novel transdermal or transmucosal drug delivery system and dosage form to deliver a pharmaceutical substance in a controlled fashion for an extended period of time in an efficient manner. More particularly this invention relates to a dosage form comprising a polyethylene material having particular physical characteristics impregnated with a liquid or semi solid drug formulation.
(b) Prior Art
Transdermal and transmucosal delivery systems for pharmaceutical substances are well known in the art. Most such delivery systems comprise a dosage form to deliver the substance in a controlled manner as part of an enclosing bandage or application means for protecting the dosage form from the atmosphere during storage and means for affixing the dosage form to the patient's skin after application. A particularly effective transdermal delivery system is that described in Tsuk U.S. Pat. No. 4,627,429 and a particularly effective transmucosal delivery system is that described in Tsuk U.S. Pat. No. 3,972,995, each of which patents is incorporated herein by reference in its entirety.
Each of the Tsuk patents describes a dosage form to be included in the drug delivery system, the dosage form comprising a porous material such as polyurethane foam. It has been found that dosage forms made from polyurethane are subject to degradation from certain solvents used for medications and, not being heat sealable, are difficult to attach to suitable backings.
Transdermal and transmucosal delivery systems generally comprise in addition to a disk shaped dosage form containing the medication an occlusive or protectant material applied to the back of the disk, usually be heat sealing, and an adhesive coating applied to the front of the disk or by a non-occlusive tape applied over the occlusive backing and extending beyond the perimeter of the disc.